Did a Giant Comet Barely Miss the Earth in 1883?

A re-analysis of an obscure report by a Mexican astronomer suggests that a fragmented comet bigger than Halley's Comet came within a few hundred miles of wiping us all out.

The human race could have gone the way of the dinosaurs if the fragments of a giant comet that is now believed by Mexican astronomers to have passed within a few hundred miles of Earth in 1883 had struck our planet.

Earlier this year, Hector Manterola, Maria de la Paz Ramos Lara, and Guadalupe Cordero of Mexico City's National Autonomous University of Mexico published a new analysis of observations made by Mexican astronomer Jose Bonilla in the late summer of 1883. Bonilla, stationed at a small observatory in Zacatecas, Mexico, observed 450 objects passing across the face of the sun on Aug. 12 and 13, according to an M.I.T. Technology Review recap of the new paper by Manterola and his colleagues.

Bonilla reported his observations in 1886 in L'Astronomie, a French scientific journal of the time. Since the Mexican astronomer appears to have been the only one to have seen the "misty" collection of stellar objects passing through the sky, his account was not given much credencethe editor of L'Astronomie, for example, claimed the objects were likely "birds, insects, or dust passing in front of Bonilla's telescope."

But in reviewing the report, Manterola and his colleagues say they now believe Bonilla was looking at the fragments of an enormous comet that had recently broken apart. The reason other astronomers around the world didn't see them was that only Bonilla was watching from an observatory positioned on Earth with the proper line of sight to see the fragments as they passed across the face of the Sun. The Pons-Brooks comet observed by others in 1883, however, may have been the same one Bonilla saw, the researchers contend.

The re-analysis of Bonilla's account suggests that the "mist" surrounding the objects in the sky and their close proximity to each other are strong indicators that a broken-up comet passed by Earth nearly 120 years ago. Manterola, Lara, and Cordero believe the fragments may have missed our planet by as little as 370 miles or so.

What's more, they believe Bonilla observed more than 3,000 objects over two dayseach as big or bigger than the object that struck in 1908 near the Podkamennaya Tunguska River with the blast force of 1,000 Hiroshima bombs. The Mexican researchers contend the original, unbroken comet's size might have been eight times that of Halley's Comet.

An object that size striking Earth would almost certainly have wiped out life as we know it, but Manterola, Lara, and Cordero note that even in fragments, a collision would have been devastating.

"So if they had collided with Earth we would have had 3,275 Tunguska events in two days, probably an extinction event," the researchers write.

More recently, Comet Lovejoy survived its scorching encounter with the sun and has gone on to become one of the most impressive comets in recent decades for Southern Hemisphere observers.

Damon Poeter got his start in journalism working for the English-language daily newspaper The Nation in Bangkok, Thailand. He covered everything from local news to sports and entertainment before settling on technology in the mid-2000s. Prior to joining PCMag, Damon worked at CRN and the Gilroy Dispatch. He has also written for the San Francisco Chronicle and Japan Times, among other newspapers and periodicals.
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